Lithographic apparatus and device manufacturing method

Abstract

Liquid is supplied to a space between the projection system of a lithographic apparatus and a substrate. A flow of gas towards a vacuum inlet prevents the humid gas from escaping to other parts of the lithographic apparatus. This may help to protect intricate parts of the lithographic apparatus from being damaged by the presence of humid gas.

The invention claimed is: 
     
       1. A lithographic apparatus, comprising:
 a substrate table configured to hold a substrate; 
 a projection system configured to project a patterned beam onto a target portion of the substrate; 
 a liquid supply system configured to at least partly fill a space between the projection system and the substrate with a liquid; 
 a member that is located above the substrate table and that extends along at least a part of the boundary of the space between the projection system and the substrate, the member configured to at least partly confine the liquid in the space; and 
 a gas inflow port separate from the body of the member and configured to create a flow of gas to at least partly confine humid gas in a volume around and in contact with the liquid in the space. 
 
     
     
       2. The apparatus according to  claim 1 , further comprising an underpressure inlet configured to remove gas. 
     
     
       3. The apparatus according to  claim 2 , wherein the underpressure inlet is configured to remove gas in contact with the liquid in a volume above the liquid. 
     
     
       4. The apparatus according to  claim 2 , wherein the underpressure inlet has an annular shape, the projection system arranged at the center of the annular shape. 
     
     
       5. The apparatus according to  claim 1 , further comprising a cover to cover at least part of the projection system, the cover configured to prevent humid gas from entering the projection system or the remainder of the lithographic apparatus. 
     
     
       6. The apparatus according to  claim 5 , further comprising a seal, wherein the seal is configured to seal the cover to the projection system. 
     
     
       7. The apparatus according to  claim 5 , wherein the seal is flexible. 
     
     
       8. The apparatus of  claim 5 , further comprising a passage between the member and the cover. 
     
     
       9. The apparatus according to  claim 1 , wherein the gas inflow port is arranged so that, in use, the flow of gas is at least partly between the member and the projection system. 
     
     
       10. The apparatus according to  claim 1 , wherein the member further comprises an outlet, on a bottom surface of the member, configured to remove liquid. 
     
     
       11. The apparatus according to  claim 10 , wherein the member is movable in Z, Rx and Ry directions. 
     
     
       12. The apparatus of  claim 1 , wherein the flow of gas is clean and dry gas. 
     
     
       13. The apparatus of  claim 1 , further comprising a passage that is between the member and the projection system and that is fluidly connected to the space. 
     
     
       14. A device manufacturing method, comprising:
 providing a liquid to a space between a projection system of a lithographic apparatus and a substrate; 
 confining the liquid in the space at least in part by a member of the lithographic apparatus located above the substrate; 
 creating a flow of gas to confine humid gas in a volume around and in contact with the liquid in the space using a gas inflow port separate from the member; and 
 projecting a patterned beam of radiation using the projection system onto a target portion of the substrate through the liquid. 
 
     
     
       15. The method according to  claim 14 , comprising flowing the gas through a passage, the passage formed at least partly by the projection system and the member. 
     
     
       16. A lithographic apparatus, comprising:
 a substrate table configured to hold a substrate; 
 a projection system configured to project a patterned beam onto a target portion of the substrate; 
 a liquid supply system configured to at least partly fill a space between the projection system and the substrate with a liquid; 
 a member that is located above the substrate table and that extends along at least a part of the boundary of the space between the projection system and the substrate, the member configured to at least partly confine the liquid in the space; 
 a gas inflow port configured to create a flow of gas to at least partly confine humid gas in a volume around and in contact with the liquid in the space; and 
 a gas outflow port configured to remove gas from the flow of gas. 
 
     
     
       17. The apparatus of  claim 16 , wherein the gas outflow port is formed in a structure separate from the projection system and the member. 
     
     
       18. The apparatus of  claim 16 , wherein the flow of gas is clean and dry gas. 
     
     
       19. The apparatus of  claim 16 , wherein the member further comprises an outlet that is on a bottom surface of the member and that is configured to remove liquid. 
     
     
       20. The apparatus of  claim 16 , further comprising a passage that is between the member and the projection system and that is fluidly connected to the space.